A Penicillium expansum glucose oxidase-encoding gene, GOX2, is essential for gluconic acid production and acidification during colonization of deciduous fruit.
Mol Plant Microbe Interact
; 25(6): 779-88, 2012 Jun.
Article
em En
| MEDLINE
| ID: mdl-22352719
ABSTRACT
Penicillium expansum, the causal agent of blue mold rot, causes severe postharvest maceration of fruit through secretion of total, d-gluconic acid (GLA). Two P. expansum glucose oxidase (GOX)-encoding genes, GOX1 and GOX2, were analyzed. GOX activity and GLA accumulation were strongly related to GOX2 expression, which increased with pH to a maximum at pH 7.0, whereas GOX1 was expressed at pH 4.0, where no GOX activity or extracellular GLA were detected. This differential expression was also observed at the leading edge of the decaying tissue, where GOX2 expression was dominant. The roles of the GOX genes in pathogenicity were further studied through i) development of P. expansum goxRNAi mutants exhibiting differential downregulation of GOX2, ii) heterologous expression of the P. expansum GOX2 gene in the nondeciduous fruit-pathogen P. chrysogenum, and iii) modulation of GLA production by FeSO(4) chelation. Interestingly, in P. expansum, pH and GLA production elicited opposite effects on germination and biomass accumulation 26% of spores germinated at pH 7.0 when GOX activity and GLA were highest whereas, in P. chrysogenum at the same pH, when GLA did not accumulate, 72% of spores germinated. Moreover, heterologous expression of P. expansum GOX2 in P. chrysogenum resulted in enhanced GLA production and reduced germination, suggesting negative regulation of spore germination and GLA production. These results demonstrate that pH modulation, mediated by GLA accumulation, is an important factor in generating the initial signal or signals for fungal development leading to host-tissue colonization by P. expansum.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Penicillium
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Regulação Fúngica da Expressão Gênica
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Frutas
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Gluconatos
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Glucose Oxidase
Idioma:
En
Revista:
Mol Plant Microbe Interact
Assunto da revista:
BIOLOGIA MOLECULAR
/
BOTANICA
/
MICROBIOLOGIA
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Israel